Air moving across an array of photovoltaic (PV) assemblies mounted to the roof of a building, or other support surface, creates wind uplift forces on the PV assemblies. Much work has been done in the design and evaluation of arrays of PV assemblies to minimize wind uplift forces. See U.S. Pat. Nos. 5,316,592; 5,505,788; 5,746,839; 6,061,978; and 6,148,570. Reducing wind uplift forces provides several advantages. First, it reduces the necessary weight per unit area of the array. This reduces or eliminates the need for strengthening the support surface to support the weight of the array, thus making retrofit easier and reducing the cost for both retrofit and new construction. Second, it reduces or eliminates the need for the use of roof membrane- (or other support surface-) penetrating fasteners; this helps to maintain the integrity of the membrane. Third, the cost of transporting and installing the assembly is reduced because of its decreased weight. Fourth, lightweight PV assemblies are easier to install than assemblies that rely on ballast weight to counteract wind uplift forces. Fifth, when designed properly, the assembly can serve as a protective layer over the roof membrane or support surface, shielding from temperature extremes and ultraviolet radiation.
The invention is directed to an array of photovoltaic (PV) assemblies mountable to a support surface. Each PV assembly comprises a base, a PV module and a support assembly securing the PV module to a position overlying the upper surface of the base. The base comprises a main member and a cover defining the upper surface of the base; the cover comprises an electrical conductor. An electrical ground connector may be made between the covers of different PV assemblies. The cover may comprise sheet metal and may have an electrically-insulating surface layer. The main member may be a thermal insulator and the cover may comprise a low-emissivity layer. The covers of adjacent PV assemblies may be interengaged so that wind uplift forces on one of the PV assemblies tend to transfer to adjacent the assemblies so to help counteract the wind uplift forces.
Other features and advantages of the invention will appear from the following description in which the preferred embodiments have been set forth in detail in conjunction with the accompanying drawings.